WO2014157786A1

WO2014157786A1 - Method for canceling interference in wireless communication system and apparatus therefor

Info

Publication number: WO2014157786A1
Application number: PCT/KR2013/007972
Authority: WO
Inventors: 김은선; 박종현; 서한별; 김기준; 김형태
Original assignee: 엘지전자 주식회사
Priority date: 2013-03-27
Filing date: 2013-09-04
Publication date: 2014-10-02
Also published as: EP2981001A4; CN105191174B; EP2981001A1; KR20150135210A; JP6470803B2; JP2018014732A; CN105191174A; KR102214070B1; US20190182707A1; JP2016509430A; EP2981001B1; US10257744B2; US10924961B2; JP6251292B2; US20160021565A1

Abstract

According to an embodiment of the present invention, disclosed is a method for supporting, by a serving base station, cancelation of interference signals from signals received at a target terminal in a wireless communication system. The method comprises the steps of: receiving scheduling information of at least one neighboring base station from the at least one neighboring base station; configuring a set of auxiliary information for canceling the interference signals of a target terminal on the basis of the scheduling information of the at least one neighboring base station; and transmitting the set of auxiliary information for canceling the interference signals of the target terminal to the target terminal, wherein the auxiliary information comprises at least one of demodulation reference signal (DM-RS) related information and cell-specific reference signal (CRS) related information in association with interference signals from respective neighboring base stations.

Description

【Specification】

[Name of invention]

Method and apparatus for canceling interference in wireless communication system

Technical Field

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for supporting interference cancellation in a wireless communication system.

Background Art

[2] Various devices and technologies, such as smartphone-to-machine communication (M2M) and smart phones and tablet PCs, which require high data transmission rates, have been introduced and spread. Accordingly, the amount of data required to be processed in the cellular network is increasing very quickly. To meet this rapidly increasing data processing demand, carrier aggregation (CA) technology, cognitive radio technology, etc., to efficiently use more frequency bands, and data capacity transmitted within a limited frequency Multi-antenna technology, multi-base station cooperation technology, etc. to improve the performance is being developed. In addition, the communication environment is evolving in the direction of increasing the density of nodes that can be accessed from the user equipment. A node is a fixed point capable of transmitting / receiving a radio signal with a user device having one or more antennas. A communication system having a high density of nodes can provide a higher performance communication service to the user equipment by cooperation between nodes.

[3] This multi-node cooperative communication method, in which a plurality of nodes communicate with a user equipment using the same time-frequency resources, performs communication with a user equipment without mutual cooperation by operating each node as an independent base station. It has much better performance in data throughput than its communication method.

[4] A multi-node system employs a plurality of nodes, each node acting as a base station or access point, antenna, antenna group, radio remote header (RRH), radio remote unit (RRU). To perform cooperative communication. Unlike conventional centralized antenna systems in which antennas are centrally located at a base station, in a multi-node system, the plurality of nodes are typically located more than a certain distance apart. The plurality of nodes may be managed by one or more base station or base station controllers that control the operation of each node or schedule data to be transmitted / received through each node. Can be. Each node is connected to a base station or base station controller that manages the node via a cable or dedicated line.

[5] This multi-node system can be regarded as a kind of MIMOC multiple input multiple output system in that distributed nodes can simultaneously transmit and receive different streams to communicate with a single or multiple user equipment. However, the multi-node system ^• system, so the transmission signals using the distributed nodes in various locations, the transmission region relative to the antenna with the conventional jeungang centralized antenna system, each antenna has to cover is reduced. Therefore, compared to the existing system implementing the MIM0 technology in the centralized antenna system, the transmission power required for each antenna to transmit a signal can be reduced in the multi-node system. In addition, since the transmission distance between the antenna and the user equipment is shortened, path loss is reduced, and high-speed data transmission is possible. Accordingly, the transmission capacity and power efficiency of the cell system may be increased, and the position of the user equipment in the cell may be increased. Regardless, relatively uniform quality of communication performance can be satisfied. In addition, in a multi-node system, since the base station (s) or base station controller (s) connected to the plurality of nodes are responsible for data transmission / reception, signal loss incurred in the transmission process is reduced. In addition, when nodes located more than a predetermined distance perform cooperative communication with the user equipment, correlation and interference between antennas are reduced. Therefore, according to the multi-node cooperative communication scheme, a high signal to interference-plus-noise ratio (SINR) can be obtained.

[6] Due to the advantages of the multi-node system, in order to enjoy the cost of base station expansion and backhaul network maintenance in the next generation mobile communication system, and to expand service coverage and channel capacity and SINR, Multi-node systems are emerging as a new foundation for cell communication by replacing or replacing existing centralized antenna systems.

[Detailed Description of the Invention] [Technical Issues]

The present invention proposes a scheme for supporting efficient interference cancellation in a wireless communication system. In addition, the present invention is to provide a method of using specific information used for the purpose of the discussion as a condition for interference cancellation.

[9] The technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems which are not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the following description. Could be.

Technical Solution

According to an embodiment of the present invention, a method for supporting a removal of an interference signal from a received signal of a target terminal by a serving base station in a wireless communication system is disclosed. Receiving scheduling information; Constructing a set of auxiliary information for removing an interference signal of a target terminal based on the scheduling information of the at least one garment base station; And transmitting to the target terminal a set of auxiliary information for removing the interference signal of the target terminal, wherein the auxiliary information is associated with an interference signal from each neighboring base station.

It may include at least one of cel 1 specific reference signal (CRS) related information or demodulat ion reference signal (DM-RS) related information.

Preferably, the CRS-related information includes at least one of a cell identifier associated with the CRS, a number of ports for transmitting the CRS, a CRS frequency shift, an MBSFN subframe pattern, and a transmission power ratio of the CRS to the PDSCH. It may include one.

Preferably, the DM-RS related information may include at least one of a cell identifier related to the DM-RS and a scrambling identity (nSCID) related to the DM ᅳ RS.

Preferably, the auxiliary information includes precoding matrix information used for transmitting the interference signal, tank information, physical downlink shared channel (PDSCH) start symbol index information of the interference signal, and a modulation order of the interference signal, or It may further include at least one MCS level information.

Preferably, the auxiliary information may further include CSI-RSC channel state information reference signal (QSI) related information or CRS related information capable of a quasi co-located (QCL) assumption with the DM-RS. [0015] Preferably, the auxiliary information includes PDSCH resource mapping information of the interference signal, wherein the PDSCH RE mapping information is CRS related information, non-zero power CSI-RS index associated with the interference signal. And zero power CSI—RS at least one.

Preferably, the auxiliary information may include an ABS most blank subframe (pattern) pattern of the neighboring base station.

[17] Preferably, the neighboring base station. When the ABS pattern is included, the auxiliary information may be valid only for the ABS indicated by the ABS pattern.

Preferably, the auxiliary information may include a transmission mode of a terminal scheduled to receive the interference signal.

Preferably, the method may further include transmitting information indicating one of the set of auxiliary information to the target terminal.

Preferably, the basic unit of the resource allocation area may be set equally between the serving base station and the neighboring base station for the interference support.

[21] A base station configured to support removal of an interference signal from a received signal of a target terminal in a wireless communication system according to another embodiment of the present invention, the base station comprising: a radio frequency (RF) unit; And a processor configured to control the RF unit, wherein the processor receives scheduling information of the at least one neighboring base station from at least one neighboring base station and is targeted based on scheduling information of the at least one neighboring base station. Configure a set of auxiliary information for removing the interference signal of the terminal, and transmit a set of auxiliary information for removing the interference signal of the target terminal to the target terminal, the auxiliary information from each neighboring base station It may include at least one of ceU-specific reference signal (CRS) related information or DM-RS (demodulation reference signal) related information related to the interference signal.

[22] A method for a terminal to remove an interference signal from a received signal in a wireless communication system according to another embodiment of the present invention, wherein the method is an auxiliary for removing an interference signal from at least one neighboring base station. Receiving a set of information from the serving base station; Receiving information indicating at least one of the set of auxiliary information; And estimating the interference signal based on the indicated at least one auxiliary information and removing the interference signal from the received signal. At least one of the cell-specific reference signal (CRS) related information or DM-RS (demdu 1 at ion reference signal) related information related to the interference signal from each neighboring base station to be viewed, and the at least one auxiliary information indicated above May be associated with a neighbor base station, which may cause interference to the terminal among the neighbor base stations.

[23] A method for a terminal to remove an interference signal from a received signal in a wireless communication system according to another embodiment of the present invention, comprising: providing a set of auxiliary information for removing the interference signal from at least one neighboring base station; Receiving from a serving base station; Receiving information indicating an interference candidate subset of the set of auxiliary information; And blindly searching for an interference signal in the received signal using the indicated interference candidate subset, and removing the found interference signal from the received signal, wherein the assistance information is provided for each base station. And at least one of information related to cel 1-speci fic reference signal (CRS) or information related to demodu 1 ati on reference signal (DM-RS) related to an interference signal from the neighboring base station. Among them, it may be associated with neighboring base stations that are likely to cause interference to the terminal.

[24] A terminal configured to remove an interference signal from a received signal in a wireless communication system according to another embodiment of the present invention, the terminal comprising: a radio frequency (RF) unit; And a processor configured to control the RF unit, the processor receiving a set of auxiliary information from the serving base station for removing an interference signal from at least one neighboring base station and indicating at least one of the set of auxiliary information. Receive the information, estimate the interference signal based on the indicated at least one auxiliary information, and remove the interference signal from the received signal, wherein the auxiliary information includes an interference signal from each neighboring base station; At least one of related CRS (ceH-specific reference signal) related information or information related to demodu 1 ati on reference signal (DM-RS), wherein the indicated at least one auxiliary information interferes with the terminal among the neighboring base stations. It may be associated with neighboring base stations that are likely to cause

[25] A terminal configured to remove an interference signal from a received signal in a wireless communication system according to another embodiment of the present invention, wherein the terminal is a radio frequency (RF). unit; And a processor configured to control the RF unit, the processor receiving a set of supplementary information from a serving base station for removing an interference signal from at least one neighboring base station, and a subset of interference candidates among the set of supplementary information. Receive information indicating a, blindly search for an interference signal in the received signal using the indicated interference candidate subset, and remove the detected interference signal from the received signal, wherein the auxiliary information is respectively And at least one of cen-specif ic reference signal (CRS) related information or demodulation reference signal (DM-RS) related information related to the interference signal from the base station, wherein the indicated interference candidate subset is selected from neighboring base stations. Neighboring base stations that are likely to cause interference to the mobile station May be related.

The above-mentioned solutions are only some of the embodiments of the present invention, and various embodiments reflecting the technical features of the present invention will be described below by those skilled in the art. It can be derived and understood based on the detailed description.

Advantageous Effects

According to an embodiment of the present invention, it is possible to efficiently perform interference cancellation in a wireless communication system.

In addition, an embodiment of the present invention can increase resource utilization because specific information used for other purposes is used as a condition for interference cancellation.

[29] In a wireless communication system, a coordinated multiple-point transmission and reception (CoMP) set can be efficiently determined.

[30] The effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above are clearly described to those skilled in the art from the following description. Will be understood.

[Brief Description of Drawings]

The accompanying drawings, which are included as a part of the detailed description to help understand the present invention, provide an embodiment of the present invention, and together with the detailed description, describe the technical idea of the present invention. 1 shows an example of a radio frame structure used in a wireless communication system.

2 shows an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system. ᅳ

3 illustrates a downlink (DL) subframe structure used in a 3GPP LTE / LTE-A system.

4 shows an example of an uplink (UL) subframe structure used in 3GPP LTE / LTE-A system.

[36] Figure 5 illustrates a Multiple Input Multiple Output (MIMO) system to which embodiment (s) of the present invention are applied.

[37] Figure 6 shows a block diagram of an apparatus for implementing embodiment (s) of the present invention. [Form for conducting invention]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. Therefore, one skilled in the art knows that the present invention may be practiced without these specific details.

In some cases, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In the present invention, a user equipment (UE) may be fixed or mobile, and various devices for transmitting and receiving user data and / or various control information by communicating with a base station (BS) It belongs to this. UE (Terminal Equipment, MSCMobile Station), MXMobi Le Terminal), UT Jser Terminal (SS), Subscribe Station (SS), Wireless Device (Wireless Device), Personal Digital Assistant (PDA), Wireless Modem, Mobile It may be called a handheld device or the like. In addition, in the present invention, the three BS generally refers to a fixed station that communicates with the UE and / or another BS, and communicates with the UE and another BS to exchange various data and control information. BS is ABS (Advanced It may be called other terms such as a base station (Node-B), an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, an access point, and a PSC processing server. In the following description of the present invention, BS is collectively referred to as eNB.

In the present invention, a node refers to a fixed point capable of transmitting / receiving a radio signal by communicating with a user equipment. Various forms of eNBs may be used as nodes regardless of their name. For example, the node may be a BS, an NB, an eNB, a picocell cell eNB (PeNB), a home eNB (HeNB), a relay, a repeater, and the like. Also, the node may not be an eNB. For example, it may be a remote radio head (remote radio head, RRH), the wireless remote units ^{(radio remote unit ', RRU)} .醒, RRU, etc. generally have a power level lower than the power level of the eNB (power level). Since RRH or RRU or below, RRH / RRU is generally connected to eNB by dedicated line such as optical cable, it is generally compared with RRH / RRU compared to cooperative communication by eNBs connected by wireless line. Cooperative communication by the eNB can be performed smoothly. At least one antenna is installed at one node. The antenna may mean a physical antenna or may mean an antenna port, a virtual antenna, or an antenna group. Nodes are also called points. Unlike conventional centralized antenna systems (ie, single node systems) where antennas are centrally located at base stations and controlled by a single eNB controller, multi-node systems In plural nodes, the plurality of nodes are usually spaced apart by more than a certain interval. The plurality of nodes may be managed by one or more eNBs or eNB controllers that control the operation of each node or schedule data to be transmitted / received through each node. Each node may be connected to an eNB or eNB controller managing the node through a cable or a dedicated line. In a multi-node system, the same cell identifier (ID) may be used or different cell IDs may be used for signal transmission / reception to / from a plurality of nodes. When a plurality of nodes have the same cell ID, each of the plurality of nodes behaves like some antenna group of one cell. If the nodes in the multi-node system have different cell IDs, such a multi-node system may be called a multi-cell (eg, macro-cell / femto-cell / picoquet cell) system. When the multiple cells formed by each of the plurality of nodes are configured to be overlaid according to coverage, the network formed by the multiple cells is particularly called a multi-tier network. The cell ID of the RRH / RRU and the cell ID of the eNB may be the same. Some may be different. When the RRH / RRU uses eNBs with different cell IDs, both the RH / RRU and the eNB operate as independent base stations.

In the multi-node system of the present invention to be described below, one or more eNBs or eNB controllers connected to a plurality of nodes are configured to simultaneously transmit or receive signals to a UE through some or all of the plurality of nodes. You can control multiple nodes. Differences exist between multi-node systems depending on the identity of each node, the implementation of each node, etc., but in that multiple nodes participate together in providing communication services to the UE on a given time-frequency resource. node system are single-node system (e.g., CAS, MIM0 conventional system, the conventional relay system, a conventional repeater system, etc.) and ^'differ. Accordingly, embodiments of the present invention regarding a method for performing data cooperative transmission using some or all of a plurality of nodes may be applied to various types of multi-node systems. For example, although a node generally refers to an antenna group spaced apart from another node by a predetermined distance or more, embodiments of the present invention described later may be applied to a case in which the node means any antenna group regardless of the interval. For example, in case of an eNB having a cross-polarized (X-pol) antenna, embodiments of the present invention may be applied when the eNB controls a node configured as an H-pol antenna and a node configured as a V-pol antenna. All.

[43] Transmit / receive a signal through a plurality of transmit (Tx) / receive (Rx) nodes, transmit / receive a signal through at least £ 1 selected from a plurality of transmit / receive nodes, or downlink A communication technique for differentiating a node transmitting a signal from a node receiving an uplink signal is called multiple -eNBMIMO or CoMP (Coordinated Mul-Point TX / RX). These nodes can be classified into joint processing (BC) and scheduling coordinat ion (JP). The former is divided into joint tr ansmissi on (JT) / joint reception (JR) and dynamic point selection (DPS). The latter can be divided into coordinated scheduling (CS) and coordinated beamforming (CB). DPS is also called dynamic cell select ion (DCS). Compared to other cooperative communication techniques, more diverse communication environments can be formed when JP is performed among cooperative communication techniques among nodes. JT in JP refers to a communication scheme in which a plurality of nodes transmit the same stream to the UE, and JR refers to a communication technique in which a plurality of nodes receive the same stream from the UE. The UE / eNB synthesizes the signals received from the plurality of nodes and stores the text. Restore the rim In the case of JT / JR, since the same stream is transmitted from / to a plurality of nodes, reliability of signal transmission may be improved by transmit diversity. DPS in JP refers to a communication technique in which a signal is transmitted / received through one node selected according to a specific rule among a plurality of nodes. In the case of DPS, since a node having a good channel state between the UE and the node will be generally selected as a communication node, the reliability of signal transmission can be improved.

Meanwhile, in the present invention, a cell refers to a certain geographic area in which one or more nodes provide a communication service. Therefore, in the present invention, communication with a specific cell may mean communication with an eNB or a node that provides a communication service to the talk cell. In addition, the downlink / uplink signal of a specific cell means a downlink / uplink signal to / from an eNB or a node providing a communication service to the specific cell. A cell that provides uplink / downlink communication service to a UE is particularly called a serving cell. Further, the channel state / quality of a particular cell is determined by that particular cell. Channel state / quality of a channel or communication link formed between an eNB or a node providing a communication service and a UE. In a 3GPP LTE-A based system, a UE transmits a downlink channel state from a specific node on a channel channel state information reference signal (CSI-RS) resource to which the antenna port (s) of the specific node is assigned to the specific node. Can be measured using CSI-RS (s). In general, adjacent nodes transmit corresponding CSI 'RS resources on CSI' RS resources that are orthogonal to each other. Orthogonality of CSI-RS resources means that CSI-RS is defined by CSI—RS resource configuration, subframe offset, and transmission period that specify the symbols and subcarriers that carry CSI ᅳ RS. This means that at least one subframe configuration, CSI-RS sequence enhancement specifying different subframes is different from each other.

[45] In the present invention, Physical Downlink Control CHannel (PDCCH) / Physical Control Format Indicator CHannel (PCFICH) / PHI CH (Physical Hybrid automatic retransmit request Indicator CHanne 1) / PDSCH (Physi cal Downlink Shared CHannel) are respectively DCI (Downlink). Control Informati on) / CFI (Control Format Indicator) / Downlink ACK / NACK (ACKnow 1 / Negat i ve ACK) / Downlink data that carries a set of time-frequency resources or a set of resource elements. PUCCH (Physical Uplink Control CHannel) / PUSCH (Physi cal Uplink Shared CHannel) / PRACH (Physical Random Access CHannel) refers to a set of time-frequency resources or a set of resource elements that carry a UCKUpl ink control format) / uplink data / random access signal, respectively. In the present invention, in particular, PDCCH / PCF I CH / PH I CH / PDSCH / PUCCH / PUSCH / PRACH is assigned to the time-frequency resource or resource element (Resource Element, RE), respectively, PDCCH / PCF I CH / PH I CH / PDSCH / PUCCH / PUSCH / PRACH RE or

It is called PDCCH / PCF I CH / PH I CH / PDSCH / PUCCH / PUSCH / PRACH resource. Hereinafter, the expression that the user equipment transmits PUCCH / PUSCH / PRACH is used in the same sense as transmitting uplink control information / uplink data / random access signal on or through the PUSCH / PUCCH / PRACH, respectively. In addition, the expression that the eNB transmits the PDCCH / PCF ICH / PHICH / PDSCH is used in the same meaning as transmitting downlink data / control information on or through the PDCCH / PCFICH / PHICH / PDSCH, respectively.

1 illustrates an example of a radio frame structure used in a wireless communication system. In particular, Figure i ( _a ) is in the 3GPP LTE / LTE-A system. Figure 1 shows a frame structure for frequency division duplex (FDD) used, Figure 1 (b) shows a frame structure for time division duplex (TDD) used in 3GPP LTE / LTE-A system .

Referring to FIG. 1, a radio frame used in a 3GPP LTE / LTE-A system has a length of 10 ms (307200.Ts) and is composed of 10 equally sized subframes (SF). . Numbers may be assigned to 10 subframes in one radio frame. Here, Ts represents a sampling time and is represented by Ts = l / (2048 * 15kHz). Each subframe has a length of 1ms and consists of two slots. 20 slots in one radio frame may be sequentially numbered from 0 to 19. Each slot is 0.5ms long. The time for transmitting one subframe is defined as a transmission time interval (ΤΉ). The time resource may be classified by a radio frame number (also called a radio frame index), a subframe number (black is also called a subframe number), a slot number (or a slot index), and the like.

The radio frame may be configured differently according to the duplex mode. For example, in the FDD mode, since downlink transmission and uplink transmission are separated by frequency, a radio frame is either a downlink subframe or an uplink for a specific frequency band. Only one of the link subframes is included. In the TDD mode, since downlink transmission and uplink transmission are separated by time, a radio frame includes both a downlink subframe and an uplink subframe for a specific frequency band.

[49] Table 1 illustrates a DL-UL configuration of subframes in a radio frame in the TDD mode.

[50] [Table 1]

This (special) subframe is indicated. The singular subframe includes three fields of Down ink ink TimeSlot (DwPTS), Guard Period (GP), and U link Pilot TimeSlot (UpPTS). DwPTS is a time interval reserved for downlink transmission, and UpPTS is a time interval reserved for uplink transmission. Table 2 illustrates the configuration of specific subframes (conf igurat ion).

[52] [Table 2]

2 shows an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system. In particular, FIG. 2 shows a structure of a resource grid of a 3GPP LTE / LTE-A system. There is one resource grid per antenna port.

Referring to FIG. 2, the pilot includes a plurality of 0rthogonal frequency division multiplexing (0FDM) symbols in the time domain and includes a plurality of resource blocks (RBs) in the frequency domain. An OFDM symbol may mean a symbol period. Degree

2, the signal transmitted in each slot is ^ * ^V , c subcarriers

It may be represented by a resource grid composed of a subcarrier and OFDM symbols. here,

Is the resource block (RB) of the downlink slot

M ^UL K [denotes the number of ^DL M ^UL , and ^ RB denotes the number of RBs in the UL slot. ^ RB and ^V «s

It depends on the DL transmission bandwidth and the UL transmission bandwidth, respectively.

OFDM in downlink slot

N ^UL N ^RB

Indicates the number of symbols, and ^symb indicates the number of OFDM symbols in a UL slot. ^V − represents the number of subcarriers constituting one RB.

The OFDM symbol may be called an OFDM symbol, SC—FDM symbol, or the like according to a multiple access scheme. The number of OFDM symbols included in one slot may vary according to the channel bandwidth and the length of the CP. For example, in case of a normal CP, one slot includes 7 OFDM symbols. In case of an extended CP, one slot includes 6 OFDM symbols. Although FIG. 2 illustrates a subframe in which one slot includes 7 OFDM symbols for convenience of description, embodiments of the present invention can be applied to subframes having other numbers of OFDM symbols in the same manner. 2, the angle

OFDM symbol, in the frequency domain

Includes subcarriers Subconveying The wave type may be divided into a data subcarrier for data transmission, a reference signal subcarrier for transmission of a reference signal, a null subcarrier for a guard band, and a DC component. The null subcarrier for the DC component is a subcarrier left unused, and the OFDM signal generation process is mapped to a carrier frequency (carrier freqeuncy, f0) during frequency upconversion. The carrier frequency is also called the center frequency.

N

[56] One RB is defined as (eg, 7) consecutive OFDM symbols in the time domain, and is defined by (eg, 12) consecutive subcarriers in the frequency domain. . For reference, a resource composed of one OFDM symbol and one subcarrier is called a resource element (RE) or tone. Therefore, one RB is

It consists of three resource elements. Each resource element in the resource grid may be uniquely defined by an index pair (k, 1) in one slot. k is from 0 in the frequency domain

-RS

The index given by V «s * ^V ^ -1 is 1 and the index assigned from 0 to ^symb mb 1 in the time domain.

Two RBs occupying one consecutive subcarrier in one subframe and one located in each of two slots of the subframe are referred to as a physical resource block (PRB) pair. Two Bs constituting a PRB pair have the same PRB number (or also referred to as a PRB index). VRB is a kind of logical resource allocation unit introduced for resource allocation. VRB has the same size as PRB. According to the mapping method of the VRB to the PRB, the VRB is divided into a localized type VRB and a distributed type VRB. Localized type VRBs are mapped directly to PRBs, so that a VRB number (also called a VRB index) corresponds directly to a PRB number. That is, nPRB = nVRB. Localized VRBs are numbered from 0 to NDLVRBVR 1 in order. NDLVRB = NDL B. Therefore, according to the localization mapping method, VRBs having the same VRB number are mapped to PRBs having the same PRB number in the first slot and the second slot. On the other hand, the distributed type VRB is mapped to the PRB through interleaving. Thus, a distributed type VRB with the same VRB number maps to a different number of PRBs in the first and second slots. Can be pinged. Two PRBs, one located in two slots of a subframe and having the same VRB number, are called VRB pairs.

3 illustrates a downlink (down 1 ink, DL) subframe structure used in a 3GPP LTE / LTE-A system.

Referring to FIG. 3, a DL subframe is divided into a control region and a data region in the time domain. Referring to FIG. 3, up to three (or four) OFDM symbols located at the front of the first slot of a subframe are assigned to a control region to which a control channel is allocated. Hereinafter, a resource region available for PDCCH transmission in a DL subframe is called a PDCCH region. The remaining OFDM symbols other than the OFDM symbol (s) used as the control region correspond to a data region to which a Physical Downlink Shared CHannel (PDSCH) is allocated. Hereinafter, a resource region available for PDSCH transmission in a DL subframe is called a PDSCH region. Examples of DL control channels used in 3GPP LTE include PCFICH (Physical Control Format Indicator Channel), PDCCH (Physical Downlink Control Channel), PHICH (Physical Hybrid ARQ indicator Channel). The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information on the number of OFDM symbols used for transmission of a control channel within the subframe. The PHICH carries a hybrid automatic repeat request (HARQ) ACK / NACK (acknow 1 edgment t / nega ti ve ^~ acknow 1 edgment) signal in response to the UL transmission.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). DCI includes resource allocation information and other control information for l) E or a UE group. For example, DCI may include a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format of an uplink shared channel (UL—SCH), and resource allocation information, a paging channel. paging information on the paging channel (PCH), system information on the DL—SCH, resource allocation information of an upper layer control message such as random access response transmitted on the PDSCH, and transmission power for individual UEs in the UE group. It includes a control command (Transmit Control Command Set), a transmit power control (Transmit Power Control) command, the act ivat ion indication information, VoIP (Downlink Assignment Index) and the like. The transmission format and resource allocation information of the DL shared channel (DL-SCH) are also called DL scheduling information or DL grant, and are also referred to as UL shared channel (DL). The transmission format and the resource allocation information of the UL—SCH are also called UL scheduling information or UL grant. The DCI carried by one PDCCH has a different size and use depending on the DCI format, and its size may vary depending on a coding rate. In the current 3GPP LTE system, various formats such as formats ◦ and 4 for uplink, formats 1, 1A, IB, 1C, 1D, 2, 2A, 2B, 2C, 3, and 3A are defined for uplink. For each use of the DCI format, call flag, RB allocation, MCSdnodulat ion coding scheme, redundancy version, NDKnew data indicator, transmit power control, and cyclic shift DMRS cycle cyclic shift demodulation reference signal Control information, such as UL index, CQ I (channel quality information) request, DL assignment index (DL assignment index), HARQ process number, TPMI (transmit precoding matrix indicator) and PMI (precoding matrix indicator) information The combination is transmitted to the UE as downlink control information.

In general, a DCI format that can be transmitted to the UE varies according to a transmission mode (TM) configured in the UE. In other words, not all DCI formats can be used for a UE configured for a particular transmission mode, but only certain DCI format (s) can be used for that particular transmission mode.

[62] The PDCCH is transmitted on aggregation of one or a plurality of consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REGs). For example, one CCE corresponds to nine REGs and one REG corresponds to four REs. In the 3GPP LTE system, a CCE set in which a PDCCH can be located is defined for each UE. The CCE set in which the UE can discover its PDCCH is referred to as a PDCCH search space, simply a search space (SS). An individual resource to which a PDCCH can be transmitted in a search space is called a PDCCH candidate. The collection of PDCCH candidates to be monitored by the UE is defined as a search space. In the 3GPP LTE / LTE-A system, the search space for each DCI format may have a different size, and a dedicated search space and a common search space are defined. A specific discovery space, configured for each individual UE. The common search space is configured for a plurality of UEs. The following illustrates aggregation levels that define search spaces.

[63] [Table 3]

One PDCCH candidate corresponds to 1, 2, 4, or 8 CCEs according to a CCE aggregation level. The eNB sends the actual PDCCH (DCI) on any PDCCH candidate in the search space, and the UE monitors the search space to find the PDCCH (DCI). Herein, monitoring means attempting decoding of each PDCCH in a corresponding search space according to all monitored DCI formats. The UE may detect its own PDCCH by monitoring the plurality of PDCCHs. Basically, since UE does not know where its PDCCH is transmitted, every subframe attempts to decode the PDCCH until all PDCCHs of the corresponding DCI format have detected the PDCCH having their own identifiers. It is called blind detection (blind decoding).

The eNB may transmit data for the UE or the UE group through the data region. Data transmitted through the data area is also called user data. In order to transmit user data, a physical downlink shared channel (PDSCH) may be allocated to the data area. A paging channel (PCH) and a DL ink-shared channel (DL ^- SCH) are transmitted through the PDSCH. The UE may read data transmitted through the PDSCH by decoding control information transmitted through the PDCCH. Information indicating to which UE or UE group data of the PDSCH is transmitted, how the UE or UE group should receive and decode PDSCH data, and the like are included in the PDCCH and transmitted. For example, a specific PDCCH is masked with a cyclic redundancy check (CRC) with a Radio Network Temporary Identity (RNTI) of "A", and a radio resource (eg, frequency location) of "B" and a transmission type information of Assume that information about data transmitted using (eg, a transport block size, modulation scheme, coding information, etc.) is transmitted through a specific DL subframe. The UE monitors the PDCCH using its own RNTI information, and the UE having the RNTI "A" detects the PDCCH, and the PDSCH indicated by "B" and "C" through the received PDCCH information. Receive

For demodulation of a signal received by the UE from the eNB, a reference signal reference signal (RS) to be compared with the data signal is required. The reference signal refers to a signal of a predetermined special waveform that the eNB and the UE know from each other, the eNB transmits to the UE, and the UE transmits to the eNB, also called a pilot (pi lot). Reference signals are divided into a cell-specific RS shared by all UEs in a cell and a demodulation ion RS (DMRS) dedicated to a specific UE. The DMRS transmitted by the eNB for demodulation of downlink data for a specific UE may also be referred to as UE-specific RS. In downlink, the DM RS and the CRS may be transmitted together, but only one of the two may be transmitted. However, when only the DM RS is transmitted without the CRS in the downlink, the DM RS transmitted by applying the same precoder as the data may be used only for demodulation purposes, and thus a channel measurement RS should be provided separately. For example, in 3GPP LTE (-A), in order to enable the UE to measure channel state information, an additional measurement RS, CSI-RS, is transmitted to the UE. CSI 사실 RS is transmitted every predetermined transmission period consisting of a plurality of subframes, unlike the CRS transmitted in every subframe based on the fact that the channel state is relatively small over time.

4 shows an example of an uplink (UL) subframe structure used in a 3GPP LTE / LTE-A system.

Referring to FIG. 4, a UL subframe may be divided into a control region and a data region in the frequency domain. One or several physical uplink control channels (PUCCHs) may be allocated to the control region to carry uplink control information (UCI). One or several PUSCHs may be allocated to a data region of a UL subframe to carry user data.

In a UL subframe, subcarriers having a long distance based on a direct current (DC) subcarrier are used as a control region. In other words, subcarriers located at both ends of the UL transmission bandwidth are allocated for transmission of uplink control information. DC subcarrier before signal This component is left unused for the transmission and is mapped to the carrier frequency fO during the frequency upconversion process. The PUCCH for one UE is allocated to an RB pair belonging to resources operating at one carrier frequency in one subframe, and the RBs belonging to the RB pair occupy multiple subcarriers in two slots, respectively. The PUCCH allocated in this way is expressed as that the RB pair allocated to the PUCCH is frequency hopped at the slot boundary. However, if frequency hopping is not applied, the RB pair occupies the same subcarrier.

[70] The PUCCH may be used to transmit the following control information.

SR: Scheduling Request (SR): Information used for requesting an uplink UL-SCH resource. It is transmitted using 00 (0n-0ff Keying) method.

[72]-HARQ-AC: A response to a PDCCH and / or a response to a downlink data packet (eg codeword) on a PDSCH. It indicates whether the PDCCH or PDSCH has been successfully received. HARQ-ACK1 bits are transmitted in response to a single downlink codeword, and HARQ-ACK 2 bits are transmitted in response to two downlink codewords. HARQ-ACK response includes a positive ACK (simple, ACK), negative ACK (hereinafter NACK), DTXCDiscont inuous Transmission) or NACK / DTX. Here, the term HARQ-ACK is commonly used with HARQ AC / NACK, ACK / NACK.

[73]-CSK Channel State Information: Feedback information (downlink iniormat ion) for the downlink channel. Multiple Input Multiple Output (MIM0) —Relevant feedback information includes the RK ank indicator and the PMK Precoding Matrix Indicator.

The amount of uplink control information (UCI) that a UE can transmit in a subframe depends on the number of SC-FDMA available for transmission of control information. SOFDMA available for UCI means the remaining SC— FDMA symbol except for the SC-FDMA symbol for transmission of the reference signal in the subframe, and in the case of a subframe including a Sounding Reference Signal (SRS), the last SC of the subframe. FDMA symbols are also excluded. The reference signal is used for coherent detection of the PUCCH. PUCCH supports various formats according to the transmitted information. Table 4 below shows the mapping relationship between the PUCCH format and UCI in the LTE / LTE-A system.

[75] [Table 4]

[76] Referring to Table 4, the PUCCH format 1 series is mainly used to transmit ACK / NACK information, and the PUCCH format 2 series is mainly channel state information (CSI) such as CQI / PMI / RI. The PUCCH format 3 series is mainly used to transmit ACK / NACK information.

[77] Coordinated Multiple Point transmission and reception (CoMP) in general

In accordance with the improved system performance requirements of the 3GPP LTE-A system, CoMP transmission and reception technology (sometimes referred to as MIM0, collaborative MIM0 or network MIM0) has been proposed. CoMP technology can increase the performance of the UE located at the cell-edge and increase the average sector throughput.

[79] In general, in a multi-cell environment with a frequency reuse factor of 1, the performance and average sector yield of UEs located in cell-boundary due to inter-cell interference (ICI) This can be reduced. In order to reduce this ICI, the existing LTE system uses a simple passive technique such as fractional frequency reuse (FFR) through UE-specific power control to locate the cell boundary in an interference-limited environment. There are few ways to ensure that the UE has adequate yield performance. Was used. However, rather than lowering the use of frequency resources per cell, it may be more desirable to reduce ICI or reuse ICI as a signal desired by the UE. In order to achieve the above object, CoMP transmission scheme may be applied.

CoMP schemes applicable to downlink can be classified into joint-processing (JP) techniques and coordinated scheduling / beamforming (CS / CB) techniques.

[81] The JP technique may use data at each point (base station) of the CoMP cooperative unit. CoMP cooperative unit means a set of base stations used in a cooperative transmission scheme, and may also be referred to as a CoMP set. The JP technique can be classified into a joint transmission technique and a dynamic cell selection technique.

A joint transmission scheme refers to a scheme in which a PDSCH is transmitted from a plurality of points (part or all of CoMP cooperative units) at a time. In other words, data transmitted to a single UE may be simultaneously transmitted from a plurality of transmission points. According to the joint transmission technique, the quality of a received signal can be improved coherently or non-coherent ly, and can also actively cancel interference to another UE. . ^.

[83] The dynamic 3/4 selection scheme refers to a scheme in which a PDSCH is transmitted from one point (of CoMP cooperative units) at a time. That is, data transmitted to a single UE at a specific time point is transmitted from one point, and at that point, other points in the cooperative unit do not transmit data to the corresponding UE, and a point for transmitting data to the UE is dynamically Can be selected.

Meanwhile, according to the CS / CB scheme, CoMP cooperative units may cooperatively perform the broadforming of data transmission for a single UE. Here, data is transmitted only in the serving cell, but user scheduling / beamforming may be determined by coordination of cells of a corresponding CoMP cooperative unit. On the other hand, in the case of uplink, cooperative or coordinated multi-point reception means receiving a signal transmitted by coordination of a plurality of geographically separated points. CoMP schemes applicable to uplink can be classified into joint reception (JR) and coordinated scheduling / beam forming (CS / CB). [0086] The JR scheme means that a signal transmitted through a PUSCH is received at a plurality of reception points. The CS / CB scheme means that a PUSCH is received only at one point, but user scheduling / beamforming is performed on cells of a CoMP cooperative unit. Means determined by the adjustment.

[87] In the case of multiple UL points (ie, receiving points (RPs)), it is referred to as UL CoMP, and DL points (ie, transmission points (TPs)) The plural cases may be referred to as DL CoMP.

[88] Enhanced-PDCCH (EPDCCH) General

In LTE systems after LTE release 11, due to insufficient capacity of PDCCH and inter-cell interference due to Co P (Coordinate Multi Point), MU-MIM0 (Multi User-Multiple Input Multiple Output), etc. As a solution to the reduction of PDCCH performance, Enhanced-PDCCH (EPDCCH), which can be transmitted through the conventional PDSCH region, is considered. In addition, in order to obtain a precoding gain, EPDCCH may perform channel estimation based on DMRS, unlike conventional CRS based PDCCH.

[0090] EPDCCH transmission may be divided into localized EPDCCH transmission and distributed EPDCCH transmission according to the configuration of a PRB pair used for EPDCCH transmission. Local EPDCCH transmission means that the ECCE used for one DCI transmission is adjacent in the frequency domain, and specific precoding may be applied to obtain a bumping gain. For example, local EPDCCH transmission may be based on the number of consecutive ECCEs corresponding to the aggregation level. On the other hand, distributed EPDCCH transmission means that one EPDCCH is transmitted in a PRB pair separated in the frequency domain, and has a gain in terms of frequency diversity. For example, distributed EPDCCH transmission may be based on ECCE consisting of four EREGs included in each of the PRB pairs separated in the frequency domain.

In order to receive / acquire control information (DCI) through the EPDCCH, the UE may perform blind decoding similarly to the existing LTE / LTE-A system. In more detail, the UE may attempt (monitor) decoding a set of EPDCCH candidates for each aggregation level for DCI formats corresponding to the configured transmission mode. Here, a set of EPDCCH candidates to be monitored may be called an EPDCCH terminal talk search space, and this search space may be set / configured for each aggregation level. In addition, the aggregation level is somewhat different from the existing LTE / LTE-A system described above, depending on the subframe type, the length of the CP, the amount of available resources in the PRB pair, etc. {1, 2, 4, 8, 16, 32 } Is possible. In case of a terminal configured with EPDCCH, indexes of REs included in a PRB pair set are indexed into an EREG, and the EREG is indexed again in ECCE units. The control information can be received by determining the EPDCCH candidate constituting the search space based on the detected ECCE and performing blind decoding, where the EREG is in the REG of the existing LTE / LTE-A and the ECCE is in the CCE. As a grand concept, one PRB pair may include 16 EREGs.

In addition, for each serving cell, higher layer signaling may allow one UE to configure one or two EPDCCH PRB sets for PDCCH monitoring.

[94] TPs capable of temporarily participating in CoMP using a CSI-RSC channel state information reference signal (CSI) resource defined as a CoMP measurement set in a 3GPP LTE Rel-11 UE A channel may be estimated for the CSI, and the CSI of the PMKprecoding matrix indicator (CQI), the channel quality indicator (CQI), the RKrank indicator (CQ), etc. are fed back to the serving cell based on the estimated channel value. In the network, a dynamic point selection (DPS) scheme for selecting a TP having a relatively good channel quality based on the feedback CSI information to perform data transmission to the UE, and the TPs participating in the actual CoMP control scheduling and beamforming. Coordinated scheduling / coordinated beamforming (CS / CB) techniques for reducing mutual interference, and a joint transmission (JT) technique in which a TP participating in an actual CoMP transmits the same data to the UE may be set.

The present invention relates to information and network cooperation schemes provided by a network (or eNB) for improving the reception signal performance of a UE having a high performance receiver having interference cancellation (IC) capability.

In general, cellular mobile communication systems reach the system capacity limit as an interference-limited system by inter-cell interference in urban environments. In the case of transmitting multi-layer signals of multiple beams at one eNB by applying the MIM0 transmission technique, the inter-layer inter-cell interference is one of the major factors that determine the limit of system capacity. Therefore, in order to reduce inter-cell interference and intra-cell interference, the importance of standardization and development of cooperative transmission and high performance receiver methods is highlighted and a lot of efforts have been made.

[97] The downlink CoMP scheme is a technique for setting up a transmission beam to minimize intercell interference and intracell interference in a transmitter based on channel state information reported from a receiver. Although the complexity of the UE is not greatly increased during the data reception process, the performance of the CoMP scheme is largely determined by the accuracy of channel state information reporting. In contrast, the high-performance receiver method is a technique of obtaining better reception performance by using the characteristics of the interference signal at the receiving end. How the UE acquires information about the interference signal transmitted along with the signal signaled to it (that is, the required signal). It becomes important. Representative example of high performance receiver method

[98]-linear 醒 SE IRC receiver,

[99]-Maximum likelihood detection receiver,

[100]-interference cancellation receiver

[101], and the better the performance, the more information on the interference signal is needed. For example, an iterative decoding interference cancellation receiver, which is known to have the best performance, needs to decode the interference signal and regenerate the interference signal to cancel the interference. Is all you need.

In the present specification, a description will be given of a technique of removing the interference ^' signal from a received signal after demodulation without demodulating the interference signal. In particular, a method of removing co-scheduled interference signals will be described based on interference cancellation using DM-RS of interference signals under the assumption that PDSCH is transmitted based on DM-RS.

However, if the PDSCH co-scheduled to the RB scheduled in a specific IE is an interference signal, the eNB should provide information on the interference signal to the UE in order to remove the interference signal. In order to estimate the interference level using DM 一 RS, the UE needs to know the sequence of the DM-RS of the interference signal, and for this purpose, the eNB must provide seed information of the DM-RS sequence of the interference signal to the UE. The UE estimates / removes the interference signal using the seed information of the DM-RS sequence. .

First, if the type of interference received by a specific UE is classified, there may be a signal of another layer scheduled to the specific UE itself. As shown in (a) and (b) of FIG. 5, in the case of single-sal SU-MIM0 and multi-¾ SU-MIM0, interference from other layers _co -scheduled to a particular RB is detected. It should be removed. In this case, all the necessary information for interference cancellation is included in the DL control channel transmitted to the UE. Unlike (a) and (b) of FIG. 5, (c) and (d) of FIG. 5 illustrate a case in which the UE does not receive control information for an interference signal when receiving control information for a PDSCH. It was. 5 (c) and (d) respectively show examples of single-cell MU-MIM0 and hyper-cell MLH1IM0. In this specification, a technique for improving interference cancellation performance of a receiver of a UE is proposed based on the examples illustrated in FIGS. 5C and 5D.

Embodiment (s) of the present invention are described below, and it is assumed herein that a received signal received by the UE is composed of a desired signal and an interference signal. That is, the required signal is a downlink signal scheduled to the UE, and the interference signal corresponds to a downlink signal scheduled by one UE (s) other than the UE.

In addition, the UE (s) scheduled herein to receive the interference signal

Refer to "Interfering UE".

[108] First Embodiment

First, in the case of the single cell MU_MIM0 of FIG. 5C, since the scheduling is performed at one eNB, cooperation between eNBs is not necessary. Since both the required signal (that is, the signal scheduled to the UE) and the interfering signal are transmitted from a single eNB, when these two kinds of signals are DM-RS based signals, the seed value of the DM-RS sequence of the corresponding signal is single. set

{

} Is selected within. Therefore, if the UE knows nSCII {0, l} used in the interference signal, it can generate a DM-RS sequence, and can estimate the channel value of the interference signal using the generated DM-RS sequence. In addition, the eNB signals the entire bandwidth of the PDSCH that the eNB schedules in that subframe, in addition to the bandwidth 0 ^" 311 of the required signal for the purpose of reporting the DM-RS density used for the scheduled PDSCH transmission PRB. In addition, the eNB modulates the modulation order of the interference signal transmitted to the interfering UE in addition to information on the tank (or number of scheduled layers) used for each nSCID in the corresponding subframe and the required signal to a specific UE. If an interference signal is transmitted in two codewords and if the modulation order is the same in both codewords, signaling over by informing one modulation order value and giving the information that the modulation order is the same Reduce head

In summary, in the embodiment as shown in FIG. 5C, the eNB may provide the following information to the UE so that the UE estimates the interference using the RS of the interference signal. [111] · If the interference signal is a DM-RS based PDSCH,

[112] ^■ Whether the nSCID used for generating the DM-RS sequence of the interfering signal or the nSCID not used for the required signal is used for the interfering signal.

[113] -n number of layers (tanks) by nSCID

[114] ^■ Total number of scheduled tanks in the subframe

[115] ^« Modulation order by codeword (nSCID)

[116] If the interference signal is a CRS based PDSCH,

[117] ^■ Seed value (physical cell identifier) information of CRS sequence of interference signal, number of CRS ports, CRS frequency shift, MBSFN configuration information

[118] ^■ Transmitted PMKTPMI Information of Interference Signals

[119] -PMI restriction information: Interference eNB may help interference estimation by using only a specific TPMI set. In the case of single cell operation, codebook restriction information can be passed. In the case of a multi-cell, this information must be transmitted between the eNBs and this information must be transmitted to the UE. Or information indicating that a particular TPMI has not been used, so that only in these indications the UE will blindly find the PMI of the interfering UE within a limited set.

Information about such an interference signal may be included in downlink control information (DCI) for a required signal and may be dynamically transmitted. The eNB transmits the control information of the interference signal together with the control information for the signal required when transmitting the control information to the UE. For example, as shown in the table below, the DCI to the UE provides additional information for interference cancellation by the eNB, and the UE uses this to estimate the interference level and to remove the interference from the entire received signal.

[121] [Table 5]

[122] Second Embodiment

[123] Hereinafter, an embodiment of network signaling to help interference cancellation of a UE when multi-cell MU-MIM0 scheduling is performed in a network as shown in FIG. 5 (d) will be described. All. In the scenario as shown in FIG. 5D, a plurality of UEs are scheduled in the same PRB, and the target. The UE receives auxiliary information (or control information) for canceling the interference signal from its serving cell in order to increase the reception performance of the required signal.

[124] In more detail, in order to provide auxiliary information for removing interference signals to the target UE in the scenario as shown in (d) of FIG. 5, since the scheduling information of the neighbor cell needs to be known, network coordination between _e NBs is required. ) Is necessary. Depending on the speed and latency of the backhaul link between the eNBs, the degree of cooperation between the eNBs may vary, and the type of information that may signal the UE may vary.

[125] There are three main categories of white link.

[126] Ideal Backhaul (Non-X2) Link: As considered in the existing LTE Rel.ll CoMP, cooperating eNBs form a kind of CoMP cluster, and cells in the same CoMP cluster perform cooperative scheduling and cooperative data transmission and reception. For this purpose, it is connected by a backhaul link such as a high-capacity and low-latency fiber, which enables cooperative scheduling, and cooperative data transmission is possible because it is kept exactly in time synchronization. In addition, when receiving signals transmitted from cells in a CoMP cluster participating in cooperative transmission, the difference in reception timings of signals transmitted from each cell due to a propagation delay difference from each cell is caused by the cyclic prefix of the OFDM symbol. (cyclic prefix; CP) can be assumed to be within the length. In this case, most of the necessary information including dynamic information that can be changed every subframe can be provided to the UE more accurately by dynamic signaling in order to help the UE remove interference in every subframe.

[127] Slow backhaul link: A general backhaul link having a latency of several ms to several tens of ms, and a link capable of transmitting dynamic information for cooperation between eNBs. Inter-eNB co-operation on such a link is only possible to the extent that it delivers semi-static information to neighbor eNBs.

[128] Fast Backhaul Link: As an incremental backhaul of an ideal backhaul link and a slow backhaul link, some degree of rapid inter-eNB cooperation (e.g., latency of less than 1 ms) may be possible. The helpful information to the UE may help the interference cancellation of the UE as dynamic signaling for the limited information in addition to the information about the semi-static neighbor eNB.

In the case of the multi-cell MU-MIM0 as shown in FIG. 5 (d), information to be provided from the network for the target UE to remove the interference signal is as follows. As in FIG. 5C In this paper, a method of eliminating and / or suppressing interference by performing demodulation only without decoding an interference signal will be described in detail.

[130] 2-1. Interference signal is DM-RS based signal

[131] When estimating the interference amount of the interference signal and removing it by using the DM-RS, the seed value of the DM-RS sequence is basically required. In the case of receiving interference from the neighboring cell instead of the serving cell, the neighboring cell Cell ID values (virtual cell ID, physical cell ID) and nSCID information used to generate the DM-RS sequence used for this UE scheduling. In addition, some of channel estimation of CSI-RS and CRS, which are denser than DM-RS, may be used to increase DM-RS estimation performance. LTE Rel. In 11, we defined the concept of QCUQuasi Co-Location) assumption and signaling it to the UE. That is, the eNB may provide information on which CSI-RS and which CRS and QCL can be assumed by the interfering DM—RS sequence to the target UE. In order to find the DM ᅳ RS density in the corresponding subframe, the total tank information in the PRB scheduled by the target UE in the corresponding subframe is also required, and the information includes rank information for each (VCID, nSCID) pair. By signaling to the same effect can be obtained. In addition, modulation / order for each code word of the interference signal may be signaled to the target UE.

Hereinafter, a method of signaling the above-described information will be described. Although the specific signaling scheme will vary depending on the speed and latency of the backhaul link, the present invention proposes a signaling scheme considering the ideal backhaul link from the most conservative signaling scheme considering the slow backhaul link.

Even if it is difficult to exchange dynamic information between eNBs for UE scheduling information that varies in every subframe, auxiliary information for removing interference signals may be provided semi-statically to the UE. That is, the eNB selects candidate cells for potential interference with the target UE, receives DM-RS sequence related information and QCL information used by the cells from the corresponding cells, and receives auxiliary information for removing the interference signal. May be configured and provided to the target UE through higher layer signaling. In addition, the eNB may explicitly indicate one of the set of auxiliary information to the target UE through a PDCCH (indicated by "Bit value" in Table 6 below). The target UE may estimate and remove the interference signal based on one set of the assistance information. In case that dynamic information can be exchanged between eNBs for UE scheduling information that varies in every subframe, the eNB identifies characteristics of an interference signal to be transmitted in a current subframe through information exchange with a neighboring cell, The target UE selects and informs only a partial set from the aggregation of the supplementary information already provided through physical layer signaling, and thus, the target UE searches for a DM-RS sequence of interference signals in the partial set to perform interference estimation. Can be.

In the above two cases, the target UE utilizes a set of auxiliary information provided from the eNB, thereby causing interference in a candidate set. It detects whether a signal (that is, an interfering PDSCH signal) exists in the corresponding subframe. That is, in the former case, the auxiliary information indicated by the PDCCH may be used, and in the latter case, some sets (sub-sets) of the auxiliary information sets may be used. The target UE uses the provided auxiliary information (eg, CRS or DM-RS sequence information and QCL information) to determine whether a reference signal is detected in a corresponding subframe by exceeding a predetermined amount or more. The target UE estimates an interference channel from a reference signal detected by exceeding a predetermined amount or more of received energy, detects an interference PDSCH transmitted therewith, and removes reference signals and interference PDSCH signals detected from all five received signals.

[136] Table 6 below shows an example of information conveyed through semi-static signaling of such information.

[137] [Table 6]

[138] [Set of Seed Values for DM-RS Sequences]

[139] The eNB determines a candidate set that may cause dominant interference to the target UE and transmits it to the target UE as illustrated in Table 6. First, the target UE is provided with a VCID having a value ranging from 0 to 503, which is a seed value of a DM-RS sequence, and an nSCID having any one of 0 or 1. The VCID and nSCID are referred to as "DM-RS related information." For example, the nSCID may have a value of 0 or 1, and if both nSCID values 0 and 1 are used for the VCID, both of these values may inform the UE. Or in such a case, nSCID value may not be known for the VCID. That is, in Table 1 above, if both nSCID values 0 and 1 corresponding to nVCID (O) are informed, the UE generates a DM-RS sequence using nVCID (O) and nSCID = 0 to estimate interference. Also, interference may be estimated by generating a DM-RS sequence using nVCID (O) and nSCID = l.

If the nVCID (O) value is signaled and the nSCID field value is omitted, the UE generates a DM-RS sequence for all nSCID (eg, 0 and 1) values for the corresponding nVCID (O). Estimate the interference. However, if the nSCID value corresponding to a specific VCID is limited to one value as in the example of bit value = l in Table 6 above, the UE may use the DM-RS sequence of the interference signal using the VCID. is assumed to be generated by using only the specified nSCID and performs only the interference estimate for a ¾ switch when the DM-RS generated only specified nSCID ^'. For example, since only nSCID = {0} is signaled for nVCID (l), interference estimation using DM—RS sequence is performed considering nSCIDO only for nVCID (l).

[141] [Rank Restriction]

[142]. The tank limit information may inform whether the tank of the interference signal using the DM-RS is limited. If the information of the corresponding field is omitted, the UE blinds the tank information of the interference signal corresponding to the DM-RS seed value. Can be used for interference detection. However, if a specific tank value is signaled in the tank limit field, this is to inform the UE that the gold maximum rank has been limited to the specific tank value. Accordingly, the UE assumes that no rank above the signaled value is used for the DM-RS sequence (the signaled VCID value and the DM—RS sequence by nSCID) corresponding to the corresponding seed value, and interferes with the tank above. Do not search for a DM-RS sequence. For example, in Table 6 above, when bit value = 0, nSCID = 0 and nSCID = l for nVCID (O), respectively. It is used to inform the UE that an interfering DM-RS sequence is likely to be used. If the nSCID value {0,1} is all signaled without tank limitation, nVCID (O) and nSCID = 0, the DM-RS sequence is searched blindly from tank = 1 to tank = 8, and nSCID = l For, only the rank = 1 to the tank = 2 can search the DM—RS sequence to perform interference cancellation (IC). If there is no tank limit for each value of nSCID, the maximum rank value that each value can support must be promised in advance between the eNB and the UE, and if the tank limit field value is not signaled, the UE is assigned to each nSCID value. It is to blindly search the DM-RS sequence up to the maximum tank promised. 3GPP Rel. In 11, nSCID = 0, maximum tank = 8, and nSCID = l, maximum tank = 2.

By the way, when bit value = 1 of Table 6 above, nSCCH = 0 is limited to nSCID = 0, and the tank limit field is 1 at this time. In this case, the interference DM by nVCID (l) and nSCIE) informs the UE that the tank is limited to 1 and is transmitted. Therefore, the UE indicates that there are two or more tanks for the DM-RS sequence. The IC operation is performed considering only the case where tank = 1 without considering the interference. In order to provide this tank restriction information to the UE, rank coordination between eNBs is essential. That is, for a certain period of time, information about not scheduling more than a certain tank value for a specific DM-RS sequence, that is, information that will be scheduled below a specific tank, must be exchanged between eNBs.

[144] [modulation order or MCS restriction]

The modulation order restriction information is a field for indicating whether there is a restriction on the modulation order of an interference signal using a corresponding DM-RS sequence. If the information of the corresponding field is omitted, the UE blindly finds the modulation order of the interference signal corresponding to the seed value of the corresponding DM ᅳ RS sequence and utilizes the interference cancellation. However, if a specific modulation order value is signaled in the modulation order limit field, this informs the UE that the maximum modulation order is limited to the specific modulation order value, and the UE interferes by assuming the modulation order blindly for the modulation order below. Demodulating the DM-RS of the signal. Here, modulation order = {2, 4, 6} indicates QPSK, 16QAM and 64QAM, respectively. Of course, higher modulation order values may be signaled. For example, for a DM ᅳ RS signaled with a value of 4 in the modulation order limit field, the UE indicates that the corresponding DM-RS has been modulated with QPSK or 16QAM. The UE demodulates that DM—RS has been modulated with QPSK to find the coordinates in the constellation, demodulates with the assumption that it has been modulated with 16QAM. The coordinates are found at («¾3 ⁽ ; 6113 011) to determine which modulation order is modulated, and the amount of interference can be eliminated by estimating the channel of the interference signal.

As another embodiment, it is possible to accurately specify a modulation order as one of 2, 4, and 6, rather than the maximum modulation order. In this case, the specified modulation order may be indicated. In this case, the UE may increase the efficiency of interference cancellation by performing demodulation only on the corresponding modulation order. In addition, the UE may perform an operation of blind decoding at the indicated modulation order. have.

Similarly, instead of modulation order restriction, the UE may inform the modulation and coding scheme (MCS) restriction information. It does not simply inform the modulation order, but also informs the UE of the code rate along with the modulation order. That is, to inform the UE that the MCS is limited to a certain value or less. Through this, the UE knows that the interference signal corresponding to the seed value of the corresponding DM-RS sequence has been modulated and coded below a specific MCS level, and blinds the modulation and coding rate of the interference DM-RS sequence only within a given range. By searching and estimating the channel for the interference signal using the DM-RS to remove the interference. LTE Rel. The MCS table for the PDSCH defined in 11 consists of a combination of the order and the TBS (Transport Block Size) index.

[148] [Table 7}

In other words, the ICS index indicates a modulation order and a TBS index. The modulation order has a value of {2, 4, 6} as mentioned above, and indicates QPSK, 16QAM, and 64QAM, respectively. The TBS index is an indirect coding rate indicator, and the actual coding rate may be determined according to the PDSCH RB allocation and the number of layers. Therefore, when providing the MCS restriction information in the present invention, it is informed that it is limited to a certain value or less, for example, I _MCS <10 The modulation order can be specifically determined by providing MCS restriction information such as Knee-, 10 < I _MCS < This allows blind decoding to be performed within the indicated modulation order. Such MCS restriction information may be useful for the IC receiver of the UE not only for the demodulation based IC but also for the receiver of the kind such as the encoding based IC.

[150] In order to provide the modulation order or MCS restriction information to the UE, coordination for the modulation order or MCS between eNBs is essential. That is, information that a certain DM-RS sequence will not be scheduled above a certain modulation order or MCS level for a certain period of time, that is, information that will be scheduled below a certain modulation order or MCS level or a specific modulation order or MCS level. Information to be scheduled must be exchanged between eNBs. The information on the modulation order or MCS level restriction may be applied to the same case of the CRS based PDSCH interference signal. When signaling the modulation order and MCS level restriction information for the PDSCH modulated by a specific CRS, the UE may assume that the modulation order or MCS level of the corresponding interference signal is limited to the signaled value or less and perform the above-described operation.

[151] [DM-RS sequence with restrictions]

[152] The reason for limiting the inter-eNB rank limit black or modulation order (or MCS level) for the interference cancellation of the UE is to allow the target UE to properly demodulate and / or decode the interference signal. In general, since the reception SNR of the interference signal will be lower than the reception SNR of the required signal, simply providing information on the interference signal does not allow the UE to detect and eliminate the interference signal. In order to demodulate and / or decode the interference signal, the target UE can lower the rank and lower the modulation order or MCS so that the IC can be properly implemented to increase the reception performance of the required signal. The lock structure so that consequently to the IC through the network to the UE even when the cooperative scheduling, the magnetic signal means that the potential not using the ^"maximum rank or higher modulation order (or MCS) is very high. Therefore, the eNB can operate the DM-RS sequence and resources separately for improving the overall system yield and the UE yield. In other words, for UEs that are mainly located in the center of the cell and have very good geometry, the PDSCH is scheduled using a DM-RS sequence that has no restrictions on tanks or modulation schemes, and is located near the cell boundary to neighbor cells. To the interfering UE PDSCH may be scheduled by using a DM-RS sequence having a tank or a modulation scheme.

[153] [Assuming QCL]

[154] In order to enhance the performance of the interference channel estimation using the DM-S sequence, the eNB provides a QCL hypothesis together. The QCL assumption is to estimate the interference channel of a specific DM-RS sequence by taking the channel characteristic value of another RS having a higher RS density than the DM-RS and having the same or similar channel characteristics as that of the specific DM-RS sequence. This is for improving channel estimation performance of the DM-RS sequence. Exactly the QCUQuasi c location for each antenna port is 3GPP LTE Rel. Defined in 11. QCL is divided into two operations. CRS, DM-S, and CSI—RS are transmitted from the serving cell. Behaviour A shows that all antenna ports have the same channel characteristics, and demodulates the PDSCH. Therefore, DM-RS defined Behaviour B as the same channel characteristic as that of specific CSI-RS. Behavour B additionally signals DMCL RS and CSI—QCL with specific CRS to the UE for frequency characteristics as well as QCL with RS. Can also give

Thus, QCL assumptions can be passed for each sequence in a DM-RS sequence candidate group, for example, by mapping a DM-RS sequence and a specific (non-zero power) CSI—RS index. have. The scheme proposed in one embodiment of the present invention is 3GPP LTE Rel. Since it is not limited to the CoMP structure defined in 11, the CSI-RS index is not limited to the CSI-RS configured for CSI feedback of the UE in the CoMP scheme. Since the UE does not necessarily need to provide CSI feedback for the signaled CSI-RS index, it is not necessary to obtain channel characteristics of the CSI-RS as information useful for estimating a specific DM RS sequence. In other words, there may be a disadvantage in that the CSI-RS that the UE needs to measure increases. Therefore, for the purpose of estimating the interference channel for a specific DM-RS sequence, it may be more preferable to refer to information from a specific cell CRS in addition to the CSI-RS. That is, for the purpose of QCL, the CSI-RS index may be informed or the PCID of a specific cell may be informed to obtain channel characteristics from the CRS of the corresponding cell.

[156] In case of only CoMP scenario 4, it is inappropriate to inform PCID only for QCL assumption because TPs in different locations share the same PCID. Therefore, this case signals the CSI—RS index to the UE. In summary, CSI-RS for QCL assumption An index or a PCID may be signaled, and the UE refers to channel talk from the CSI-RS using only the CSI-RS index or PCID signaled in the QCL hypothesis information, or refers to the channel characteristic using the CRS corresponding to the PCID. However, when both the CSI-RS index and the PCID are signaled in the QCL information for the specific DM-RS sequence, the QCL relationship with the CRS corresponding to the signaled CSI-RS index and the signaled PCID for the specific DM-RS sequence, respectively. It is to inform that. That is, the DM-RS may be in a QCL relationship with the signaled CSI—RS index, and in some cases, may be in a QCL relationship with the CRS corresponding to the signaled PCID. Accordingly, the UE searches for interference signals by performing interference estimation for each case and performs interference cancellation.

[157] When signaling the CSI-RS index to the UE for the QCL assumption to the UE as shown in Table 6 above, the eNB provides the UE with the co-team measurement in addition to the CSI-RS configuration (conf igurat ion) for CSI measurement. CSI-RS configuration for long-term measurement) and QCL hypothesis should be signaled separately to UE. CSI-RS configuration for this may include CSI—RSs for CSI measurement.

[158] [Rate Matching Information]

CRS information of neighbor cells should also be transmitted for the purpose of indicating PDSCHRE mapping of interference signals and whether there is CRS interference in a specific RE. The CRS information includes the number of CRS antenna ports, CRS frequency shift (= {0, 1, 2, ..., 5}), and MBSFN subframe pattern. If the UE wants to remove the CRS interference by notifying the UE that there is CRS interference, the physical cell ID of the corresponding CRS is not the CRS frequency shift. That is, by reporting the physical cell ID, the number of CRS antenna ports, and the MBSFN subframe pattern as the CRS information, the UE removes the CRS interference control capability at the corresponding CRS location.

In addition, for the purpose of indicating whether there is interference from an interference signal in a specific RE, CSI-RS information and ZP CSI-RS information of a neighbor cell may also be signaled to the UE. That is, since the PDSCH of the interference signal is not mapped, the UE does not perform the IC in the corresponding REs to prevent performance degradation.

In addition, the CSI-RS index for the purpose of informing the PDSCH rate matching pattern of the interference signal may be separately signaled. Alternatively, one may use the CSI-RS index indicated for the QCL assumption. For example, in Table 6 above, let us know when bit value = 0. Since the PDSCH of the interfering signal using the DM-RS sequence generated with the quasi nVCID (O) and nSCID = {0, l} is QSI with the CSI—RS index (0), the UE has a channel from the CSI-RS index (0) While bringing the characteristic, the PDSCH of the interference signal can be recognized as being rate-matched and transmitted in a configuration corresponding to the CSI-RS index (0). In this case, no separate CSI-RS index signaling for rate matching information is necessary. However, when the CSI-RS index for the QCL and the separate CSI-RS index for the rate matching information are signaled, respectively, the rate matching for the corresponding interference signal assumed by the UE is separately transmitted CSI-RS for the rate matching information. Follow the RS index. In Table 6, a plurality of CSI-RS indexes for providing rate matching information may be signaled. Depending on the capability of the UE, interference cancellation for the CSI-RS may be performed at the E where the corresponding CSI-RS is transmitted using the received CSI-RS index or the QCL CSI-RS index as the rate matching information. have.

[162] In addition, a ZPCSI-RS index used for interfering signal transmission may also be transmitted to the UE. ZP CSI Signaled—RS may be actually muted and PDSCH may be mapped depending on which UE the interfering eNB schedules for. However, to inform the target UE through such signaling, the PDSCH may be mapped to the corresponding ZP CSI-RS, and the likelihood that the corresponding ZP CSI-RS may be muted. By using the ZP CSI 'RS, it is left to the UE to decide whether to perform the IC on the REs or not to perform the IC on the REs in the ZPCSI-RS through energy detection. Except for signaled CRS indexes and CSI-RS indexes, and unless otherwise signaled and restricted (e.g., PSS / SSS / PBCH transmission, positioning RS transmission, MBSFN subframe, etc.) In the area of to inform the UE that the PDSCH is transmitted. The UE receiving this assumes that PDSCH is transmitted in a region other than the corresponding ZP CSI-RS.

In general, the ZP CSI-RS is configured to cover the configured CSI-RS location. Therefore, ZP CSI-RS can transmit signaling covering the CSI-RS transmission location to the UE without transmitting CSI-RS information as rate matching information of the separate interference signal. That is, information indicating that the PDSCH may or may not be transmitted is signaled to the signaled ZP CSI-RS.

[164] In case there is no separate signaling of the ZP CSI-RS of the interference signal, the UE is configured with respect to the entire combination of one or a plurality of ZP CSI-RSs configured in advance. It is considered that there is a possibility that the PDSCH of the interference signal may not be mapped, and the operation of performing the IC unconditionally for the corresponding REs may not be performed. The specific IC operation in the corresponding REs depends on the UE implementation.

[165] [PDSCH starting symbol index]

[166] When removing interference received from another eNB, the PDSCH start symbol of the interference signal and the required signal should be aligned in advance between eNBs. It is not desirable to remove interference due to the CRS-based PDCCH of the neighboring cells using the DM-RS-based PDSCH. Since the OFDM symbol at which the PDSCH starts depends on the amount of control information transmitted on the PDCCH and the load at the corresponding eNB every subframe, it is very burdensome to dynamically signal the PDSCH start symbol of the neighbor cell. Accordingly, the eNB may signal the PDSCH start symbol index for each DM-RS sequence to the UE by semi-static signaling as shown in Table 6. Where the term starting PDSCH symbol index is, the interference signal using the DM-RS sequence is the signaling after the PDSCH starting symbol is ^"one means that there is no PDCCH of the interference signal. For example, at bit value = 0 of Table 6, it was signaled with PDSCH start symbol index = 2, which means that the PDCCH of the interference signal transmitted by the eNB using the DM-RS sequence corresponding to nVCID (O) is the PDSCH signaled. It is not sent after the start symbol index = 2. The PDCCH may be transmitted until the OFDM symbol index = 0, 1 (PDSCH may be transmitted), but when the OFDM symbol index ≥ 2, it is guaranteed to the UE that the PDCCH is not transmitted. Then, if the UE's required signal starts from OFDM symbol index = 1, and the signal using DM-RS sequence whose nVCID (O) is the seed value of DM-RS sequence has returned to strong interference, The UE may perform demodulation without performing an IC operation on the OFDM symbol index = 1, while performing and demodulating the IC operation on a subsequent OFDM symbol index. In other words, upon receiving the PDSCH start symbol syntax information, the UE performs the IC operation only in the region in which the PDSCH is guaranteed to be transmitted and performs the demodulation without the IC in the other region. In this case, a loss value can be reduced by lowering an additive value for an area for demodulation without IC.

In another embodiment of the present invention, the UE assumes that PDSCH of an adjacent cell always starts after a symbol to which a PDSCH that targets itself is mapped without separate signaling as shown in Table 6 for a PDSCH start symbol index. can do. To do this, start PDSCH between eNBs. Information on the symbol index should be exchanged in advance, and the information corresponding to this information, as described above, indicates that the PDCCH will not be transmitted after the specific OFDM symbol index. Should be exchanged with).

As another embodiment of the present invention, each eNB may assume the PDSCH start symbol index as conservatively as possible. The UE assumes that neighboring cells also use the maximum number of OFDM symbols that its serving cell can use for PDCCH transmission, and then performs IC for the PDSCH in the symbol. In this case, it is assumed that the UE has the same bandwidth, frame structure type, etc. of neighboring cells that interfere with its serving cell.

Similarly, coordination for a location where PDSCH and EPDCCH are transmitted between eNBs may also be exchanged in advance. EPDCCH can be demodulated using DM-RS, similar to PDSCH. 1, EPDCCH can control multiplexed control information of up to 4 UEs in one RB, thereby eliminating interference in units of PRBs or bundled PRBs. There is a group. Therefore, when the UE removes the interference signal to improve the reception performance of the required signal, the interference signal assumes that the PDSCH of another UE or another layer is transmitted unless there is additional information, and performs the interference cancellation operation. To this end, a region in which PDSCH is transmitted between eNBs and an region in which EPDCCH is transmitted are designated in advance, and such information must be exchanged in advance. The specific frequency domain black is to exchange information that the EPDCCH of the base station is transmitted in the specific time frequency domain.

[170] 2-1-1. Signaling optimization

[171] If the backhaul link is fast as previously distinguished, the eNB may transmit information to assist the UE in dynamically eliminating interference with every subframe along with semi-static signaling to the UE. For example, the UE has received information about eight candidate seed values 1 to 8 of a sequence of interfering DM-RSs, providing information that only two to four times have been used for dynamic signaling. This can reduce the number of candidates. In some cases, the eNB can accurately inform the DM-RS sequence of the interference signal by transmitting only one seed value of one DM-RS sequence to the UE. Or, it may indicate information (number of layers of the interference signal) information by dynamic signaling. In this case, the bulk information instructing the UE may vary according to the number of layers through which the UE can remove interference.

[172] 2-1-2. DM-RS Sequence Search Procedure-QCL using received signal power of assumed RSs In another embodiment of the present invention, the UE signaled with the information about the interference signal as shown in Table 6 may blindly detect the DM-RS sequence of the interference signal, but may not detect the DM-RS sequence of the interference signal. When searching for an RS sequence, the CSI signaled as a possible QCL assumption can be used, either by RS index or by CRS by physical cell ID. In other words, using CSI-RS or CRS to use a QCL assumption means that the UE measures the CSI-RS or CRS periodically or aperiodically. In this case, only when the strength of the received CSI-RS or CRS is above a certain level, it may be determined that the DM-RS associated with the CSI-RS and the CRS may act as interference. Therefore, among these it can be preferentially interference estimate the interference channel detecting a DM-RS that ^is, to perform the back I IC.

[174] 2-1-3. PRB bundling alignment

[175] In order to remove interference signals from a received signal by receiving helpful information for interference cancellation, an additional consideration is related to PRB allocation of interference signals. Consideration should be given to the frequency domain occupied by the required signal and the frequency domain occupied by the interfering signal. In other words, even if the DM-RS sequence for the interference signal is detected and the interference is estimated using the interference signal, the required amount of interference can be eliminated for the entire PRB to which the required signal is allocated.

For example, when the UE detects a DM-RS sequence A as an interference signal with respect to a specific interference signal A, and uses it to remove the interference signal from the received signal, the required signal is two consecutive signals. If PRBs are allocated and the interference signal A is allocated four consecutive PRBs, the UE may remove the interference signals from all of the allocated PRBs. However, if the required signal is allocated 4 consecutive PRBs and the interference signal A is allocated 2 consecutive PRBs, the interference signal A is not included in the entire PRB allocated by the UE without any information. Since there is no guarantee that they exist identically, the interference signal cannot be eliminated as in the former case.

Therefore, unless the UE directly informs the resource allocation information of the interference signal, the UE must promise the basic granularity for the interference cancellation between eNBs, which should be the basic unit of resource allocation for one UE. do. Preferably, the PRB bundling size and the unit capable of interference cancellation should be the same. That is, the UE receives resource allocation in the serving cell on a PRB bundling basis, and on the premise that resource allocation in a neighboring cell is also made on the same PRB bundling unit, the UE may perform interference cancellation on resources allocated thereto. Can be. In this case, an appointment for PRB bundling size and resource allocation between eNBs must be made.

[178] A specific RS sequence may assume PRB bundling, and another RS sequence may not assume PRB bundling. In other words, it is specified whether PRB bundling can be assumed per RS sequence. That is, when the line to provide information about the DM-RS of the interference signal, as shown in Table 6 above, eNB can give to whether ^"on page without that you are able to assume a PRB bundling each DM-RS sequence to the UE is also signaled.

In order for the UE to remove interference in units of PRB bundling, there should be a premise that the channels of the interference signal remain the same within the bundled PRBs. Therefore, resource allocation within that bundled PRB must be allocated locally, not distributed, and such information must be known by the UE in a particular bundled PRB that is locally allocated. IC can be performed. On the other hand, the UE can not perform IC in the distributed PRB bundling PRB. Therefore, with respect to resource allocation between eNBs, cooperation between eNBs in which resource allocation is allocated in a specific frequency domain in a distributed manner and resource allocation in a local form in a specific frequency region must be made in advance.

In addition, the PRB bundling size may be variable, and resources may be allocated in M PRB bundling units in a specific subframe and resources in N PRB bundling units in another specific subframe. Alternatively, resources may be allocated in M PRB bundling units in a specific subframe and may be allocated in PRB units in a specific subframe.

[181] 2-1-4. Heterogeneous Network (HetNet Support)

In a heterogeneous network (HetNet), when providing information referred to herein to the UE to remove the interference signal, the UE may provide additional information for interference cancellation. That is, if the macro eNB operates the ABS (Almost Blank Subframe), the specific macro eNB may determine whether to transmit PDSCH according to the ABS pattern of the macro eNB. If the ABS transmits the PDSCH at a low transmit power, the signal is unlikely to act as a dominant interference source to the neighboring pico UE. Therefore, according to the ABS pattern, the interference candidate group shown in Table 6 may be divided and signaled to the UE.

For example, the pico UE is informed of a plurality of subframe sets, and the interference candidate group for each subframe set is divided. Interference candidate group means the information listed in Table 6 above. For each subframe set, see Table 6 above. Information may be signaled respectively. Alternatively, the macro eNB may signal the information shown in Table 6 only for the subframe set corresponding to the ABS.

Meanwhile, all of the information stones described in 2.1 and the following items described above may be transmitted to the target UE, and some of them may be provided to the target UE.

[185] 2-2. If the interfering signal is a CRS-based signal

[186] If the interference signal is a CRS-based PDSCH, it describes what information the network should signal in order for the target UE to remove such CRS-based interference signal from the received signal. Since the interference signal is a CRS based PDSCH, the seed value of the CRS sequence should be known first. This seed value is the physical cell ID of the cell transmitting the CRS causing interference, and the UE further includes the number of CRS ports, the location of the CRS ports, information on the presence or absence of CRS, and a subframe in which the CRS does not exist. It is necessary to know the MBSFN subframe configuration to know the transmission scheme and RS information in.

In addition, since the transmit power of the CRS may be different from the actual PDSCH transmit power, the ratio of the PDSCH transmit power to the CRS transmit power needs to be signaled to the target UE. The PDSCH transmit power ratio to the CRS transmit power ratio needs to be signaled in both the symbol in which the CRS is transmitted and the ratio in a symbol in which the CRS is not transmitted.

If the above-mentioned physical cell ID of the cell transmitting the CRS, the number of CRS ports, the location of the CRS port, information on the presence or absence of the CRS is referred to as "CRS-related information", the target UE The interference signal channel may be estimated using the signaled CRS-related information, and the PDSCH transmission power ratio to the signaled CRS transmission power may be used to determine whether CRS-based PDSCH interference actually exists.

When the interference signal is a CRS-based PDSCH, one of the pieces of information that the UE must remove the interference signal is the transmitted precoding matrix index (TPMI) used for the transmission of the interference signal. However, it is unreasonable to provide a TPMI that dynamically varies depending on the channel state in every subframe. However, fixing the TPMI of a specific UE is not preferable because it degrades the performance of the corresponding UE. In addition, it is an excessive burden on the target UE to cause the target UE to blindly search for the PMI actually used by the interfering UE (ie, used to transmit an interference signal) among the entire PMI. Therefore, the PMI of the interfering UE can be limited without excessively reducing the performance of the interfering UE. [190] With this concept, a codebook subset 'limit can be imposed, for example, a particular UE can be restricted to report using only some PMs out of all 16 PMs. At the same time, by conveying this information to the target UE, the target UE blinds to the remaining PM (s) (i.e., the set of PMs that the interfering UE 5 can use) except for the PM whose use of the interfering UE is restricted in the codebook. The TPMI can be detected to remove the interference signal.

That is, by providing such codebook subset restriction information, the candidate of the TPMI used by the interfering UE is informed. As a result, a restriction may be applied to the collision of the interfering UE, and separately, the rank limit information of the interfering UE (or the interference signal) may be provided. Tank restriction information, PDSCH start symbol index, modulation order (or MCS level) restriction information, and information on HetNet support are the same as in the case of DM-RS based signal of 2-1 described above.

Additionally, even if the interference signal is a CRS-based PDSCH, transmission mode (TM) information of the dominant interfering UE may be transmitted together for the purpose of informing the PDSCH transmission scheme.

[193] The following illustrates information that may be signaled to the target UE when the interference signal is a CRS based signal.

[194] [Table 8]

195] 2-2-1. CRS Sequence Discovery Procedure Even when the CRS-based interference signal is removed, the UE needs to measure and monitor the CRS of the neighbor cell as a co-team. As shown in Table 8, the UE that receives the CRS-related information of a specific cell is based on the CRS. When the interference signal is to be detected, it is determined that PDSCH using the CRS may enter the interference only when the CRS received signal strength is higher than a certain level. It can be used for channel estimation and cancellation of signals.

[197] 2-2-2. Subband Size Sort

In order to remove the interference signal by receiving information helpful for interference cancellation, an additional consideration is related to subband size alignment ( _SL1 bband size alig_ent) of the interference signal. Consideration should be given to the frequency domain to which the required signal is assigned and the frequency domain to which the interference signal is assigned. Unless informed directly of the resource allocation information of the interference signal, the target UE should be promised to each other the basic granularity for interference cancellation between eNBs, which should be the basic unit of resource allocation for one UE.

[199] In addition, when the CRS-based PDSCH interference is to be removed, there must be a premise that the TPMI of the interference signal is the same without change in the unit of the frequency domain in which the target UE wants to remove the interference. Preferably, the subband size that the target UE uses for CQI reporting and the size of the frequency domain to be subjected to interference cancellation should be the same. That is, PMI is determined in units of subbands when allocating a resource from a serving cell to a target UE, and a unit in which PMI is kept identical when assigning resources from an adjacent cell to an interfering UE should be determined as the subbands. Accordingly, the target UE may perform interference cancellation in the frequency domain allocated thereto under the premise that its subband size is equal to that of the interfering UE. In this case, an appointment for subband size and resource allocation between eNBs should be made in advance.

Similarly, PRB grouping may be performed as a unit in which the TPMI remains the same. The TPMI of the interfering UE and the target UE remains the same within the PRB grouping. Information on how many PRBs to group and use for this purpose should also be promised in advance between eNBs.

On the other hand, all of the information described in the above 2.2 and below items may be transmitted to the target UE, some of them may be provided to the target UE.

[202] 2-3. When the DM-RS based signal and the CRS based signal are common as interference signals [203] In reality, interference signals for a target UE include DM—RS based PDSCH and CRS based PDSCH, and whether the corresponding UE is DM—RS based PDSCH so that the target UE removes the interference signal from the received signal. It should be able to distinguish whether it is a CRS based PDSCH, and based on this determination, it is necessary to estimate the amount of interference in the received signal and to remove the interference from the received signal.

Accordingly, when the DM-RS based PDSCH and the CRS based PDSCH are common, information about the network and operation of the UE are described. The following table includes the information described in Tables 6 and 8 described above, and the description thereof also refers to those described in relation to Tables 6 and 8.

[205] [Table 9] ^'

Table 9 above lists information to be provided to the target UE when it is not known which RS the interference signal is modulated with. First, the eNB signals whether the interference signal is a CRS based PDSCH or a DM ᅳ RS based PDSCH using the signaled TM. And according to the signaled TM, it is possible to determine the transmission scheme of the interference signal.

[207] In the case of a CRS-based TM (eg, TM4), the eNB provides CRS related information, where DM-RS related information is not provided. That is, in the case of the CRS-based TM, since the QCL assumption is not necessary, this information may be omitted.

[208] In the case of DM-RS based TM (eg, TM 10), the eNB can provide DM-RS related information as well as CRS related information.

When the target UE receives the information shown in Table 9 and removes the interference signal, the CRS is a signal that is always transmitted regardless of the transmission of the PDSCH. Assuming that there is, the DM-RS sequence is first detected blindly. Then, if it is determined that there is no DM-RS interference signal, or after removing the DM-RS based interference signal, the CRS based interference signal is estimated.

FIG. 6 is a block diagram illustrating components of a transmitter 10 and a receiver 20 for performing the embodiment (s) of the present invention. The transmission device 10 and the reception device ₂₀ are wireless communication with transmission and reception units 13 and 23 capable of transmitting or receiving wired and / or wireless signals carrying information and / or data, signals, messages, and the like. It is operatively connected to components such as the memory 12, 22, the transmission and reception units 13, 23, and the memory 12, 22, which store various kinds of information related to the communication in the system, and controls the components The apparatus includes a processor 11, 21, respectively, configured to control the memory 12, 22 and / or the transmit / receive units 13, 23 to perform at least one of the embodiments of the invention described above.

The memory 12 and 22 may store a program for processing and controlling the processors 11 and 21 and may temporarily store input / output information. Memory 12, 22 can be utilized as a buffer. The processors 11 and 21 typically control the overall operation of the various models in the transmitter or receiver. In particular, the processors 11 and 21 may perform various control functions for carrying out the present invention. Processors 11 and 21 may also be referred to as controllers or microcontrollers, microprocessors, microcomputers, etc. Processors 11 and 21 may be referred to as hardware. (hardware) or firmware (firmware), software, or a combination thereof. In the case of implementing the present invention by using hardware, applic icat ion specific i integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), and PLDs (r ogr) configured to carry out the present invention. Ammab 1 e logic devices, field programmable gate arrays (FPGAs), and the like may be provided in the processors 400a and 400b. Meanwhile, when implementing the present invention using firmware or software, software or software may be configured to include modules, procedures, or functions for performing the functions or operations of the present invention, and to perform the present invention. The configured firmware or software may be provided in the processor 11 ᅳ 21 or stored in the memory 12, 22 to be driven by the processor 11, 21.

The processor 11 of the transmission apparatus 10 may be configured to perform predetermined encoding and / or data on signals and / or data to be transmitted from the processor 11 or a scheduler connected to the processor 11 to be transmitted to the outside. After the modulation (modulation) is transmitted to the transmission and reception unit (13). For example, the processor 11 converts the data sequence to be transmitted to K layers through demultiplexing, channel encoding, scrambling, and modulation. The coded data string is also called a codeword and is equivalent to a transport block, which is a data block provided by the MAC layer. One transport block (TB) is encoded by one codeword, and each codeword is transmitted to a receiving device in the form of one or more layers. The transmit / receive unit 13 may include an oscillator for frequency upconversion. The transmit / receive unit 13 may include Nt transmit antennas, where Nt is a positive integer greater than or equal to one.

The signal processing process of the receiving device 20 consists of the inverse of the signal processing process of the transmitting device 10. Under the control of the processor 21, the transmitting and receiving unit 23 of the receiving device 20 receives a radio signal transmitted by the transmitting device 10. The transmit / receive unit 23 may include Nr receive antennas, and the transmit / receive unit 23 frequency-converts each of the signals received through the receive antenna into a baseband signal. . The transmit / receive unit 23 may include an oscillator for frequency downconversion. The processor 21 may decode and demodulate the radio signal received through the reception antenna, thereby restoring data originally intended to be transmitted by the transmitter 10. The transmission and reception units 13 and 23 are provided with one or more antennas. The antenna transmits a signal processed by the transmission / reception units 13 and 23 to the outside under the control of the processors 11 and 21, or receives a radio signal from the outside to receive the transmission / reception unit 13 , 23). Antennas are also called antenna ports. Each antenna may correspond to one physical antenna or may be configured by a combination of more than one physical antenna elements. The signal transmitted from each antenna can no longer be decomposed by the receiver 20. The reference signal (RS) transmitted for the corresponding antenna defines the antenna as viewed from the perspective of the receiving device 20, and whether the channel is a single radio channel from one physical antenna or includes the antenna. Regardless of whether it is a composite channel from a plurality of physical antenna elements, the receiver 20 enables channel estimation for the antenna. That is, the antenna is defined such that a channel for transmitting a symbol on the antenna can be derived from the channel through which another symbol on the same antenna is transmitted. In the case of a transmission / reception unit that supports a multi-input multi-out (MI M0) function for transmitting and receiving data using a plurality of antennas, two or more antennas may be connected.

In the embodiments of the present invention, the UE operates as the transmitter 10 in the uplink and the receiver 20 in the downlink. In addition, in the embodiments of the present invention, the eNB operates as the receiver 20 in the uplink, and operates as the transmitter 10 in the downlink.

The transmitter 10 or the receiver 20 may perform a combination of at least one or two or more embodiments of the present invention described above.

[217] The detailed description of the preferred embodiments of the present invention as described above is provided to enable those skilled in the art to implement and practice the present invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will understand that the present invention described in the claims can be variously modified and changed. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Industrial Applicability The present invention can be used in a communication device such as a terminal, a relay, a base station, and the like.

Claims

[Range of request]

• Claim 1

In a method for a serving base station to support the removal of the interference signal in the received signal of the target terminal in a wireless communication system

Receiving scheduling information of the neighbor base station from at least one neighbor base station; .

Configuring a set of auxiliary information for canceling an interference signal of a target terminal based on scheduling information of the at least one neighboring base station; And

Transmitting to the target terminal a set of auxiliary information for removing the interference signal of the target terminal;

The auxiliary information may include at least one of CRSCcel 1-spec ic reference signal (DM-RS) related information or DM-RS (demodulat ion reference signal) related information related to the interference signal from each neighboring base station. Support method.

[Claim 2]

The method of claim 1, wherein the CRS-related information is:

At least one of a cell identifier associated with the CRS, a number of ports for transmitting the CRS, a CRS frequency shift, an MBSFN subframe pattern, and a transmission power ratio of the CRS to the PDSCH. How to apply.

[Claim 3]

The method of claim 1, wherein the DM-RS related information is:

And at least one of a cell identifier associated with the DM-RS and a scrambling identity (nSCID) associated with the DM-RS.

[Claim 4] ᅳ

The method of claim 1, wherein the assistance information is:

Precoding matrix information, tank information, PDSCH start symbol index information of the interference signal used to transmit the interference signal And at least one of modulation order or MCS level information of the interference signal.

[Claim 5]

The method of claim 1, wherein the assistance information is:

And further including CSI-RS (CSI-RS) related information or CRS-related information capable of the quasi co-located (QCL) assumption with the DM-RS.

[Claim 6]

The method of claim 1, wherein the assistance information is:

And PDSCH resource mapping information of the interference signal, wherein the PDSCH RE mapping information includes at least one of CRS related information, non-zero power CSI-RS index, and zero power CSI-RS index related to the interference signal. The interference signal cancellation support method, characterized in that it comprises a.

[Claim 7]

The method of claim 1, wherein the assistance information is:

And including an almost blank subframe (ABS) pattern of the neighboring base station.

[Claim 8]

The method of claim 7, wherein the ABS pattern of the base station is included.

And wherein the auxiliary information is valid only for an ABS indicated by the ABS pattern.

[Claim 9]

The method of claim 1, wherein the auxiliary information includes a transmission mode of a terminal scheduled to receive the interference signal.

[Claim 10]

The method of claim 1,

And transmitting information indicating one of the set of auxiliary information to the target terminal.

[Claim 11]

The method of claim 1, wherein the serving base station and the neighboring base to support the interference The base unit of the resource allocation area is set to be the same between stations, interference signal cancellation support method.

[Claim 12]

A base station configured to support removal of an interference signal from a received signal of a target terminal in a wireless communication system,

A radio frequency (RF) unit; And

A processor configured to control the RF unit;

The processor receives scheduling information of the at least one neighbor base station from at least one neighboring base station, and sets a set of auxiliary information for removing the interference signal of the target terminal based on the scheduling information of the at least one neighboring base station. And to transmit a set of auxiliary information for removing the interference signal of the target terminal to the target terminal,

The auxiliary information may include at least one of cel 1-speci c reference signal (CRS) related information or demodulat ion reference signal (DM-RS) related information related to an interference signal from each neighboring base station. Base station.

[Claim 13]

In the method for the terminal to remove the interference signal from the received signal in a wireless communication system,

Receiving a set of auxiliary information from the serving base station for canceling the interference signal from at least one neighboring base station;

Receiving information indicating at least one set of the supplementary information; And

Estimating the interference signal based on the indicated at least one auxiliary information and removing the interference signal from the received signal,

The assistance information is associated with an interference signal from each neighboring base station.

At least one of CRSCcel 1-specif ic reference signal (DMSC) related information or DM-RS (demodulat ion reference signal) related information,

And wherein the indicated at least one auxiliary information is related to a neighboring base station which may cause interference to the terminal among the neighboring base stations.

[Claim 14]

In the wireless communication system in a terminal for removing the interference signal from the received signal,

Receiving from the serving base station a set of auxiliary information for removing interference signals from at least one neighboring base station;

Receiving information indicating the aggregation enhancement interference subset of the supplemental information; And

Blindly searching for an interference signal in the received signal using the indicated interference candidate subset, and removing the found interference signal from the received signal,

The auxiliary information may include at least one of CRSCcel 1-speci c reference signal related information or demodulat ion reference signal (DM-RS) related information related to an interference signal from each neighboring base station.

And wherein the indicated interference candidate subset is associated with neighboring base stations that are likely to cause interference to the terminal in an increase in base station base stations.

[Claim 15]

As a terminal configured to remove an interference signal from a received signal in a wireless communication system,

A radio frequency (RF) unit; And

A processor configured to control the RF unit,

The processor receives a set of auxiliary information from a serving base station to remove an interference signal from at least one neighboring base station, receives information indicating at least one of the set of auxiliary information, and at least one of the indicated Estimate an interference signal based on ancillary information of and remove the interference signal from the received signal.

The auxiliary information includes at least one of CRSCcel 1-speci fic reference signal (DM-RS) related information or DM-RS (demodulat ion reference signal) related information related to an interference signal from each neighboring base station,

The indicated at least one auxiliary information is the terminal among the neighboring base stations. Characterized by being associated with a neighboring base station that is likely to cause interference

[Claim 16]

A terminal configured to remove an interference signal from a received signal in a wireless communication system,

A radio frequency (RF) unit; And

A processor configured to control the RF unit,

The processor receives a set of supplementary information from a serving base station to remove an interference signal from at least one neighboring base station, receives information indicating a subset of interference candidates among the set of supplementary information, and indicates the indicated Blindly search for interference signals in the received signal using interference candidate subsets ^; And remove colored interference signals from the received signal,

The auxiliary information includes at least one information related to a cell-specific reference signal (CRS) or information related to a demodulat ion reference signal (DM-RS) related to an interference signal from each neighboring base station.

And wherein the indicated subset of interference candidates is associated with neighboring base stations that are likely to cause interference to the terminal among neighboring base stations.